Demands for terminals having large-sized touch screens are increasing to meet the needs of users. A variety of types of terminals with touch screens, such as smart phones, tablet personal computers (PCs), phablets, etc., are being released. However, as the size of the terminals becomes larger, it becomes more difficult for the user to manipulate the terminal with a single hand. For this reason, various types of soft or virtual keyboards (hereinafter, called ‘virtual keyboards’) are being studied for the terminals that support one-handed manipulation.
European (EU) Patent Publication No. 2450783 published on May 9, 2012 to Intel Corporation describes a configuration of a virtual keyboard for handheld devices wherein virtual keys may be arranged in arcs that are conveniently reached by a user's thumb when the handheld device is held in the user's hand, wherein the placement of the keys may be customized to fit the individual user's thumb or personal preferences.
European Patent Publication No. 2450783 describes an arc-shaped virtual keyboard is provided by first prompting the user to draw an arc with his thumb on the touch screen surface and then, if the arc is drawn by the user, recording the location of the arc on the screen display. The location of the arc may be used to determine where a row of keys of the virtual keyboard will be placed on the display screen. If more than one row is to be placed on the display screen, the user may be prompted to draw a middle arc, an outer arc, and an inner arc. Each of the arcs is referred to as a “calibration arc” because its purpose is to calibrate the location of the row of keys so the keys on the row will be at a convenient position for the user's thumb.
The user may be prompted to retrace each arc more than once so that the handheld device can determine an average position of the arc. The keys rendered based on the drawn arc support one-hand operation.
In the above prior art documents, there may be an uncomfortable reach of a thumb or other gestures when the curve of an arc is drawn on the touch screen. The user has to repeatedly perform the drawing of the curve until he feels comfortable in manipulating the virtual keyboard generated based on the curve drawn on the touch screen. Moreover, the repetitive arc calibration may require considerable time and may also bring about a keyboard configuration that does not fit the natural movement of the user's thumb.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.